Rotary piston internal combustion engine

ABSTRACT

A rotary piston internal combustion engine, particularly of trochoidal construction, which includes a rotating piston equipped at its corners with sealing bars which are constructed relatively wide for reducing wear and which are provided with slots and/or apertures for increasing their elasticity.

o United States Patent 1191 1111 3,832,104 Lamm Aug. 27, 1974 1 ROTARYPISTON INTERNAL 3,180,564 4/1965 Fuhrmann et a1. 418/122 3,182,6415/1965 Lamm 418/124 COMBUSTIOF ENGINE 3,185,387 5/1965 Paschke....418/124 Inventor: Heinz Lamm, g 3,207,426 9/1965 Gassmann et a1 418/124Bernhardt, Germany 3,245,387 4/1966 Froede 418/120 1. 3,263,913 8/1966-Fuhrmann et a1. 418/113 [73] Asslgnee: namler'Benl Aklengfieuschafi,3,270,954 9/1966 Yamamoto 418/113 stuttgart-umemerkhelm, Germany3,301,231 1/1967 Tadd 418/122 3,323,498 6/1967 Kraic et a]. 418/122 PPN05 35,177 Primary Examiner-William L. Freeh Assistant Examiner-John .1.Vrablik [30] Foreign Application Priority Data Attorney, Agent, orFirm-Craig and Antonelli ay Gerrnany 192 31 [57] ABS CT [52] US. Cl.418/113 A o y piston internal combustion g p [51] Int. CL... F01c 19/02,F04c 15/00, F0412 27/00 larly of trochoidal construction, which includesa ro- [58] Field of Search; .418/61, 1 13-124 tating piston equipped atits comers with sealing bars which are constructed relatively wide forreducing [56] References Cit d wear and which are provided with slotsand/or aper- UNITED STATES PATENTS tures for increasing theirelasticity.

3,113,526 12/1963 Paschke 418/122 13 Claims, 6 Drawing Figures ROTARYPISTON INTERNAL COMBUSTION ENGINE The present invention relates to arotary piston internal combustion engine of especially trochoidal-typeof construction with a piston that is provided at its corners withsealing bars.

The present invention is concerned with the task to construct thesealing bars more wear-resistant than known heretofore without sacrificein elasticity.

The underlying problems are solved by the present invention in that thesealing bars of solid material are constructed relatively wide for thepurpose of reducing wear and are provided with slots and/or aperturesfor increasing their elasticity.

Sealing bars are constructed for the most part from a homogeneousmaterial, for example, from piston ring material, either integral ormulti-partite. Experience, however, has demonstrated that withincreasing'sealing bar thickness, the lubricating and wear conditionsbecome more favorable. On the other hand, a thin sealing bar is moreelastic. The materials used at present have a high modulus of elasticityso that one is relegated to a thin construction. These thin sealing barsadapt themselves considerably better to the shape of the trochoidal camor running surface. The engine becomes more gas-tight and therewithachieves a higher power or output.

During idling and at small loads, a gas-tight engine is also necessaryin order to obtain an uninterrupted running, i.e., an operation freefrom misfirings. For the purpose of decreasing'the carbon monoxide valueand the hydrocarbon emission, a radially gas-tight piston, i.e.., awell-sealing sealing bar is absolutely desirable. A good adaptability ofthe sealing bar to the trochoidal cam or running surface exists onlywith a thin sealing bar (about 2 mm. However, the wear of the top of thesealing bar is not satisfactory in the cases of limitlubrication, i.e.,at the point of transition of dry friction to floating friction.

Accordingly, one aims at utilizing thicker sealing bars (about 3-6 mm.)which are equipped with a larger head radius and thus reduce the wear asa result of a larger utilizable surface. Additionally, a larger oilwedge forms on the leading side between the head portion and the runningsurface, which is of great significance for the lubrication and radialgas sealing of the piston. This lubricant wedge serves in connectionwith the metered lubrication also as oil reservoir over several workingcycles until the next small oil drop is again metered to thelubrication.

Furthermore, it is also worthy of mention that thicker sealing bars alsoproduce a more favorable heat removal.

in order to utilize completely the advantages of the thicker sealingbars, such a sealing bar has to be constructed elastically for reasonspointed out above.

in one preferred type of construction according to the presentinvention, the radius of the head portion of the sealing bar isconstructed at least equal to. half the thickness of the sealing bar.

For the purpose of increasing the elasticity, a slot may be providedextending from the bottom side of the sealing bar, preferably in thecenter of the sealing bar, whose depth corresponds approximately tothreequarters of the height of the sealing bar.

In order that the gas force becomes rapidly effective underneath thesealing bar and is not blocked off by a tilting of the sealing bar inthe piston groove, bores may be arranged in thelower portion of thesealing bar or small milled-in cuts may be provided in the lower portionof the sealing bar whose cross section preferably decreases from theoutside toward the slot. An arrangement thereof may be realized both onthe leading as also on the trailing sealing bar flank.

Another possibility to increase the elasticity of the sealing barresides in that two slots, whose depth corresponds approximately to aquarter of the width of the sealing bar, are arranged in proximity tothe head portion or in the head portion of the sealing barperpendicularly to the flanks thereof or at an angle to one-anotherwhich is not smaller than the pivot angle of the sealing bar. The headportion thus becomes elastic with respect to the lower portion of thesealing bar and the latter continues to remain a guide body in thepiston groove. For reasons of permitting as large as possible a verticalwear of the sealing bars, the lateral slots may also be arrangedsomewhat lower.

Moreover, the lower portion of the sealing bar can be constructed moreelastically in that additionally a slot is provided extending from thebottom side of the sealing bar whose depth corresponds approximately tohalf the height of the sealing bar.

For the purpose of increasing the elasticity of the sealing bar, thepresent invention further proposes that a recess or aperture, preferablytriangularly shaped in cross section, is provided extending from thebottom side of the sealing bar whose depth corresponds approximately tothree quarters of the height of the sealing bar. 7

According to a further feature of the present invention, anapproximately V-shaped recess or aperture may be arranged in a diagonaldirection of the cross section of the sealing bar, which extends from alower edge of the sealing bar.

Another possibility to increase the elasticity of th sealing bar residesin that in addition to the aforementioned preferably triangularly shapedrecess, a slot is provided in proximity to the head portion of thesealing bar extending from one of its flanks whose depth correspondsapproximately to two-thirds the width of the sealing bar.

Accordingly, it is an object of the present invention to provide arotary piston internal combustion engine equipped with sealing bars inthe comers of the piston which avoids by simple means the aforementionedshortcomings and drawbacks encountered in the prior art.

Another object of the present invention resides in a sealing bar for thecorner of a piston of a rotary piston internal combustion engine whichis more wearresistant without sacrifice in elasticity thereof.

A further object of the present invention resides in a sealing bar forthe piston corners of rotary piston internal combustion engines whichimproves the wear and lubricating conditions.

A still further object of the present invention resides in a sealing barfor the piston corners of a piston used in rotary piston internalcombustion engines which is simple in construction, improves the gastightness of the engine and reduces the wear of the sealing bar.

These and other objects, features and advantages of the presentinvention will become more obvious from the following description whentaken in connection with the accompanying drawing which shows, forpurposes of illustration only, several embodiments in accordance withthe present invention, and wherein:

FIG. 1 is a transverse cross-sectional view through a first embodimentof a sealing bar for the piston of a rotary piston internal combustionengine in accordance with the present invention;

FIGS. 2 through are cross-sectional views, similar to FIG. 1, throughfour further embodiments of a sealing bar in accordance with the presentinvention, and

FIG. 6 is a schematic cross-sectional view illustrating a rotary pistoninternal combustion engine of trochoidal construction.

Referring now to the drawing wherein like reference numerals are usedthroughout the various views to designate like parts, and moreparticularly to FIG. 1, this figure illustrates in cross section asealing bar 1 provided with a slot 2 that extends from the bottom side 3in the center of the sealing bar and whose depth correspondsapproximately to three-quarters of the height of the sealing bar 1; thefurther possibility exists with the sealing bar 1 of this embodiment toprovide in the lower portion of the sealing bar 1 in the leading as wellas in the trailing surfaces, bores 4 leading from the outside to theslot 2 and/or to provide small milled-in cuts 5 whose cross sectiondecreases essentially in the shape of a triangle from the outside in thedirection toward the slot 2. The head radius 6 of the sealing bar 1corresponds to half its thickness. Furthermore, the possibility isindicated in dash and dot lines to utilize a head radius 6a which islarger than half the thickness of the sealing bar 1.

FIG. 2 illustrates in cross section a sealing bar 1 in a different typeof construction with two oppositely disposed slots 7 and 8 which areprovided in the sealing bar 1 in proximity to its head portion 9perpendicularly to the flanks 10 and 11 thereof and whose depthcorresponds to about one-fourth the width of the sealing bar 1, with thepossibility to provide an additional slot 12 extending from the bottomside 3 of the sealing bar 1 whose depth corresponds approximately tohalf the height of the sealing bar 1. The head radius 6 of the sealingbar 1 corresponds to half of its thickness. Furthermore, as in FIG. 1,the possibility is indicated in dash and dot lines to utilize a headraduis 6a that is larger than half of the thickness of the sealing bar1.

FIG. 3 illustrates in cross section a further embodiment of a sealingbar 1 with two oppositely disposed slots 13 and 14 which are mutuallyarranged in the head portion 9 of the sealing bar I at an angle 15 thatis larger than the pivot angle 16 of the sealing bar 1, and whose depthcorresponds approximately to a quarter of the width of the sealing bar1, with the possibility to provide an additional slot 17 extending fromthe bottom side of the sealing bar 1 whose depth corresponds.

to approximately two-thirds of the height of the sealing bar 1. The headradius 6 of the sealing bar 1 is larger than half of its thickness.

FIG. 4 illustrates in cross section a fourth embodiment of a sealing bar1 with an approximately V-shaped slot-like aperture vl8 which startsfrom a lower edge 19 of the sealing bar 1 in a diagonal direction of thecross section of the sealing bar 1 and extends approximately overtwo-thirds the width of the sealing bar 1. The slotlike aperture 18, ifit is accommodated on the leading side of the sealing bar 1, servessimultaneously as gas inlet groove. The head radius 6 of the sealing bar1 is larger than half of its thickness. 1

FIG. 5 illustrates in cross section a fifth embodiment of a sealing bar1 with an approximately triangularly shaped slot-like aperture 20 whoseone side 21 is arranged parallel to a flank of the sealing bar 1 wherebyalmost the entire bottom side 3 of the sealing bar 1 is open. The height(depth) of the slot-like aperture 20 corresponds approximately tothree-quarters the height of the sealing bar 1. The possibility isadditionally indicated to provide a slot 23 in proximity to the headportion 9 of the sealing bar 1 cut-in from the flank 22 of the sealingbar 1 disposed opposite the side 21 of the slot-like aperture 20; thedepth of the slot 23 is about two-thirds the width of the sealing bar 1.The head radius 6 of the sealing bar 1 is larger than half of itsthickness.

FIG. 6 illustrates in schematic cross-section a rotary piston internalcombustion engine of trochoidal construction which includes a casing 31provided with an internal running or contact surface 36, along which thepiston 33 slides with the sealing bars 1 accommodated in grooves 34 atthe corners of the piston. Arrow 32 thereby indicates the normaldirection of rotation of the piston 33. The casting 31 is closed off onboth sides by lateral housing parts (not shown) of conventionconstruction.

While I have shown and described several embodiments in accordance withthe present invention, it is understood that the same is not limitedthereto but is susceptible of numerous changes and modifications asknown to those skilled in the art. Thus, for example, the featuresdescribed hereinabove and/or shown in the drawing as well as those ofthe claims may be utilized individually as well as in any desiredcombination with one another for the realization of the presentinvention in its most varied types of construction. Consequently, I donot wish to be limited to the details shown and described herein butintend to cover all such changes and modifications as are encompassed bythe scope of the appended claims.

I claim:

1. A rotary piston internal combustion engine with a polygonal pistonprovided at its corners with grooves accommodating sealing bars,characterized in that a sealing bar includes a solid body and isoperable as the only sealing bar in a respective piston groove and tothat end, is constructed relativey wide for reducing the wear at the topsurface thereof and is provided with at least one continuous slot-likemeans extending into the solid body of the bar for increasing theelasticity thereof, said continuous slot-like means being closed at theinner end thereof by the solid body of the bar, extendinguninterruptedly over its entire length in the longitudinal direction ofthe sealing bar and being open over its entire length in the areathereof at'least partially facing the bottom of a respective groove, and

characterized in that said slot-like means are constituted by at leastone slot and one slot-like aperture in each sealing bar completelyclosed off with respect to one another by the body of the sealing bar.

2. A rotary piston internal combustion engine with a polygonal pistonprovided at its corners with grooves accommodating sealing bars,characterized in that a sealing bar includes a solid body and isoperable as the only sealing bar in a respective piston groove and tothat end, is constructed relatively wide for reducing the wear at thetop surface thereof and is provided with at least one continuousslot-like means extending into the solid body of the bar for increasingthe elasticity thereof, said continuous slot-like means being closed atthe inner end thereof by the solid body of the bar, extendinguninterruptedly over its entire length in the longitudinal direction ofthe sealing bar and being open over its entire length in the areathereof at least partially facing the bottom of a respective groove,

characterized in that the radius of the head portion of the sealing baris at least equal to half the thickness of the sealing bar,

characterized in that said slot-like means includes a slot extendinguninterruptedly into the sealing bar from the bottom side thereof whosedepth corresponds approximately to three-quarters the height of thesealing bar, and

characterized in that bores are provided in the lower part of thesealing bar which extend substantially transversely to the longitudinaldirection of the slot.

3. A rotary piston internal combustion engine with a polygonal pistonprovided at its corners with grooves accommodating sealing bars,characterized in that a sealing bar includes a solid body and isoperable as the only sealing bar in a respective piston groove and tothat end, is constructed relatively wide for reducing the wear at thetop surface thereof and is provided with at least one continuousslot-like means extending into the solid body of the bar for increasingthe elasticity thereof, said continuous slot-like means beingclosed atthe inner end thereof by the solid body of the bar, extendinguninterruptedly over its entire length in the longitudinal direction ofthe sealing bar and being open over its entire length in the areathereof at least partially facing the bottom of a respective groove,

characterized in that the raduis of the headportion of the sealing baris at least equal to half the thickness of the sealing bar,

characterized in that said slot-like means includes a slot extendinguninterruptedly into the sealing bar from the bottom side thereof whosedepth corresponds approximately to three-quarters the height of thesealing bar, and

characterized in that small milled-in cuts are provided in the lowerportion of the sealing bar.

4. A rotary piston internal combustion engine according to claim 3,characterized in that said milled-in cuts have a cross section whichdecreases from the outside in the direction toward the slots.

5. A rotary piston internal combustion engine with a polygonal pistonprovided at its corners with grooves accommodating sealing bars,characterized in that a sealing bar includes a solid body and isoperable as the only sealing bar in a respective piston groove and tothat end, is constructed relatively wide for reducing the wear at thetop surface thereof and is provided with at least one continuousslot-like means extending into the solid body of the bar for increasingthe elasticity thereof, said continuous slot-like means being closed atthe inner end thereof by the solid body of the bar, extendinguninterruptedly over its entire length in the longitudinal direction ofthe sealing bar and being open over its entire length in the areathereof at least partially facing the bottom of a respective groove,

characterized in that the radius of the head portion of the sealing baris at least equal to half the thickness of the sealing bar, I

characterized in that said means includes a continuous slot-likeaperture extending from the bottom side of the sealing bar into thesame, whose depth corresponds approximately to three-quarters of theheight of the sealing bar, and

characterized in that said slot-like aperture is of approximatelytriangularly shaped configuration.

6. A rotary piston internal combustion engine with a polygonal pistonprovided at its comers with grooves accommodating sealing bars,characterized in that a sealing bar includes a solid body and isoperable'as the only sealing bar in a respective piston groove and tothat end, is constructed relatively wide for reducing the wear at thetop surface thereof and is provided with at least one continuousslot-like means extending into the solid body of the bar for increasingthe elasticity thereof, said continuous slot-like means being closed atthe inner end thereof by the solid body of the bar, extendinguninterruptedly over its entire length in the longitudinal direction ofthe sealing bar andbeing open over its entire length in the area thereofat least partially facing the bottom of a respective groove,

characterized in that the radius of the head portion of the sealing baris at least equal to half the thickness of the sealing bar, and

characterized in that said means includes an approximately V-shaped,continuous slot-like aperture which extends from a lower edge of thesealing bar in a diagonal direction of the cross section of the sealingbar. I

7. A rotary piston internal combustion engine with a polygonal pistonprovided at its corners with grooves accommodating sealing bars,characterized in that a sealing bar includes a solid body and isoperable as the only sealing bar in a respective piston groove and tothat end, is constructed relatively wide for reducing the wear at thetop surface thereof and is provided with at.

least one continuous slot-like means extending into the solid body ofthe bar for increasing the elasticity thereof, said continuous slot-likemeans being closed at the inner end thereof by the solid body of thebar, extendinguninterruptedly over its entire length in the longitudinaldirection of the sealing bar and being open over its entire length inthe area thereof at least partially facing the bottom of a respectivegroove,

characterized in that the raduis of the head portion of the sealing baris at least equal to half the thicknes of the sealing bar, characterizedin that said means includes a continuous slot-like aperture extendingfrom the bottom side of the sealing bar into the same, whose depthcorresponds approximately to three-quarters of the height of the sealingbar, and

characterized in that additionally a slot is provided in proximity tothe head portion of the sealing bar which extends into the same from aflank thereof, the depth of said last-mentioned slot being abouttwo-thirds the width of the sealing bar.

8. A rotary piston internal combustion engine with a polygonal pistonprovided at its corners with grooves accommodating sealing bars,characterized in that a sealing bar includes a solid body and isoperable as only bar in a respective piston groove filled out in itswidth by the bar, and to that end, is constructed relatively wide forreducing the wear and includes a head portion having a radius at leastequal to half thethickness of the sealing bar, the sealing bar beingprovided with continuous slot-like means for increasing the elasticitythereof in the form of two uninterrupted slots provided in each sealingbar whose depth corresponds approxi mately to a quarter of the width ofthe sealing bar and which extend uninterruptedly over the entire lengththereof in the longitudinal direction of the sealing bar, the two slotsextending from an outer surface of the sealing bar into the solid bodythereof so that the two slots are open over the entire length thereof atsaid surfaces, and said two slots being closed with respect to oneanother by the solid body of the sealing bar.

9. A rotary piston internal combustion engine according to claim 8,characterized in that said two slots are provided in proximity of thehead portion of the sealing bar.

10. A rotary piston internal combustion engine according to claim 8,characterized in that said two slots are provided in the head portion ofthe sealing bar.

11. A rotary piston internal combustion engine according to claim 8,characterized in that said two slots are disposed substantiallyperpendicularly to the flanks of a respective sealing bar.

12. A rotary piston internal combustion engine according to claim 8,characterized in that said two slots are arranged to one another at anangle that is at least equal to the pivot angle of the sealing bar.

13. A rotary piston internal combustion engine according to claim 8,characterized in that an additional uninterrupted slot is provided whichextends into the sealing bar from the bottom side thereof, the depth ofsaid additional slot being about half the height of the sealing bar, andsaid additional slot being in noncommunication relationship with saidtwo slots by being separated therefrom by the body of the sealing

1. A rotary piston internal combustion engine with a polygonal pistonprovided at its corners with grooves accommodating sealing bars,characterized in that a sealing bar includes a solid body and isoperable as the only sealing bar in a respective piston groove and tothat end, is constructed relativey wide for reducing the wear at the topsurface thereof and is provided with at least one continuous slot-likemeans extending into the solid body of the bar for increasing theelasticity thereof, said continuous slot-like means being closed at theinner end thereof by the solid body of the bar, extendinguninterruptedly over its entire length in the longitudinal direction ofthe sealing bar and being open over its entire length in the areathereof at least partially facing the bottom of a respective groove, andcharacterized in that said slot-like means are constituted by at leastone slot and one slot-like aperture in each sealing bar completelyclosed off with respect to one another by the body of the sealing bar.2. A rotary piston internal combustion engine with a polygonal pistonprovided at its corners with grooves accommodating sealing bars,characterized in that a sealing bar includes a solid body and isoperable as the only sealing bar in a respective piston groove and tothat end, is constructed relatively wide for reducing the wear at thetop surface thereof and is provided with at least one continuousslot-like means extending into the solid body of the bar for increasingthe elasticity thereof, said continuous slot-like means being closed atthe inner end thereof by the solid body of the bar, extendinguninterruptedly over its entire length in the longitudinal direction ofthe sealing bar and being open over its entire length in the areathereof at least partially facing the bottom of a respective groove,characterized in that the radius of the head portion of the sealing baris at least equal to half the thickness of the sealing bar,characterized in that said slot-like means includes a slot extendinguninterruptedly into the sealing bar from the bottom side thereof whosedepth corresponds approximately to three-quarters the height of thesealing bar, and characterized in that bores are provided in the lowerpart of the sealing bar which extend substantially transversely to thelongitudinal direction of the slot.
 3. A rotary piston internalcombustion engine with a polygonal piston provided at its corners withgrooves accommodating sealing bars, characterized in that a sealing barincludes a solid body and is operable as the only sealing bar in arespective piston groove and to that end, is constructed relatively widefor reducing the wear at the top surface thereof and is provided with atleast one continuous slot-like means extending into the solid body ofthe bar for increasing the elasticity thereof, said continuous slot-likemeans being closed at the inner end thereof by the solid body of thebar, extending uninterruptedly over its entire length in thelongitudinal direction of the sealing bar and being open over its entirelength in the area thereof at least partially facing the bottom of arespective groove, characterized in that the raduis of the head portionof the sealing bar is at least equal to half the thickness of thesealing bar, characterized in that said slot-like means includes a slotextending uninterruptedly into the sealing bar from the bottom sidethereof whose depth corresponds approximately to three-quarters theheight of the sealing bar, and characterized in that small milled-incuts are provided in the lower portion of the sealing bar.
 4. A rotarypiston internal combustion engine according to claim 3, characterized inthat said milled-in cuts have a cross section which decreases from theoutside in the direction toward the slots.
 5. A rotary piston internalcombustion engine with a polygonal piston provided at its corners withgrooves accommodating sealing bars, characterized in that a sealing barincludes a solid body and is operable as the only sealing bar in arespective piston groove and to that end, is constructed relatively widefor reducing the wear at the top surface thereof and is provided with atleast one continuous slot-like means extending into the solid body ofthe bar for increasing the elasticity thereof, said continuous slot-likemeans being closed at the inner end thereof by the solid body of thebar, extending uninterruptedly over its entire length in thelongitudinal direction of the sealing bar and being open over its entirelength in the area thereof at least partially facing the bottom of arespective groove, characterized in that the radius of the head portionof the sealing bar is at least equal to half the thickness of thesealing bar, characterized in that said means includes a continuousslot-like aperture extending from the bottom side of the sealing barinto the same, whose depth corresponds approximately to three-quartersof the height of the sealing bar, and characterized in that saidslot-like aperture is of approximately triangularly shapedconfiguration.
 6. A rotary piston internal combustion engine with apolygonal piston provided at its corners with grooves accommodatingsealing bars, characterized in that a sealing bar includes a solid bodyand is operable as the only sealing bar in a respective piston grooveand to that end, is constructed relatively wide for reducing the wear atthe top surface thereof and is provided with at least one continuousslot-like means extending into the solid body of the bar for increasingthe elasticity thereof, said continuous slot-like means being closed atthe inner end thereof by the solid body of the bar, extendinguninterruptedly over its entire length in the longitudinal direction ofthe sealing bar and being open over its entire length in the areathereof at least partially facing the bottom of a respective groove,characterized in that the radius of the head portion of the sealing baris at least equal to half the thickness of the sealing bar, andcharacterized in that said means includes an approximately V-shaped,continuous slot-like aperture which extends from a lower edge of thesealing bar in a diagonal direction of the cross section of the sealingbar.
 7. A rotary piston internal combustion engine with a polygonalpiston provided at its corners with grooves accommodating sealing bars,characterized in that a sealing bar includes a solid body and isoperable as the only sealing bar in a respective piston groove and tothaT end, is constructed relatively wide for reducing the wear at thetop surface thereof and is provided with at least one continuousslot-like means extending into the solid body of the bar for increasingthe elasticity thereof, said continuous slot-like means being closed atthe inner end thereof by the solid body of the bar, extendinguninterruptedly over its entire length in the longitudinal direction ofthe sealing bar and being open over its entire length in the areathereof at least partially facing the bottom of a respective groove,characterized in that the raduis of the head portion of the sealing baris at least equal to half the thicknes of the sealing bar, characterizedin that said means includes a continuous slot-like aperture extendingfrom the bottom side of the sealing bar into the same, whose depthcorresponds approximately to three-quarters of the height of the sealingbar, and characterized in that additionally a slot is provided inproximity to the head portion of the sealing bar which extends into thesame from a flank thereof, the depth of said last-mentioned slot beingabout two-thirds the width of the sealing bar.
 8. A rotary pistoninternal combustion engine with a polygonal piston provided at itscorners with grooves accommodating sealing bars, characterized in that asealing bar includes a solid body and is operable as only bar in arespective piston groove filled out in its width by the bar, and to thatend, is constructed relatively wide for reducing the wear and includes ahead portion having a radius at least equal to half the thickness of thesealing bar, the sealing bar being provided with continuous slot-likemeans for increasing the elasticity thereof in the form of twouninterrupted slots provided in each sealing bar whose depth correspondsapproximately to a quarter of the width of the sealing bar and whichextend uninterruptedly over the entire length thereof in thelongitudinal direction of the sealing bar, the two slots extending froman outer surface of the sealing bar into the solid body thereof so thatthe two slots are open over the entire length thereof at said surfaces,and said two slots being closed with respect to one another by the solidbody of the sealing bar.
 9. A rotary piston internal combustion engineaccording to claim 8, characterized in that said two slots are providedin proximity of the head portion of the sealing bar.
 10. A rotary pistoninternal combustion engine according to claim 8, characterized in thatsaid two slots are provided in the head portion of the sealing bar. 11.A rotary piston internal combustion engine according to claim 8,characterized in that said two slots are disposed substantiallyperpendicularly to the flanks of a respective sealing bar.
 12. A rotarypiston internal combustion engine according to claim 8, characterized inthat said two slots are arranged to one another at an angle that is atleast equal to the pivot angle of the sealing bar.
 13. A rotary pistoninternal combustion engine according to claim 8, characterized in thatan additional uninterrupted slot is provided which extends into thesealing bar from the bottom side thereof, the depth of said additionalslot being about half the height of the sealing bar, and said additionalslot being in non-communication relationship with said two slots bybeing separated therefrom by the body of the sealing bar.